1. Field of the Invention
The present invention relates to a suspension apparatus including a hydraulic suspension device (e.g., a so-called “hydraulic suspension cylinder”) and at least two accumulators which are connected to the suspension device.
2. Discussion of Related Art
Each of Patent Document 1 (Japanese Patent Application Publication No. 63-130419), Patent Document 2 (Japanese Patent Application Publication No. 63-78806), and Patent Document 3 (Japanese Patent Application Publication No. 63-49512) discloses a suspension apparatus including a hydraulic suspension cylinder provided for a wheel of a vehicle, two accumulators connected to the suspension cylinder, and a switchable valve provided between the two accumulators.
When, in the above suspension apparatus, the switchable valve is switched between a closed state thereof and an open state thereof, the number of the accumulator(s) that communicates or communicate with the suspension cylinder is changed, and accordingly a spring constant of the two accumulators as a whole is changed between a high value and a low value.